The JPA standard defines how to access JDBC connections from enterprise beans. OpenJPA also provides APIs to retrieve a connection directly from the EntityManagerFactory's DataSource.

The EntityManager.unwrap(java.sql.Connection.class) method returns an EntityManager's connection. If the EntityManager does not already have a connection, it will obtain one. The returned connection is only guaranteed to be transactionally consistent with other EntityManager operations if the EntityManager is in a managed or non-optimistic transaction, if the EntityManager has flushed in the current transaction, or if you have used the OpenJPAEntityManager.beginStore method to ensure that a datastore transaction is in progress. Always close the returned connection before attempting any other EntityManager operations. OpenJPA will ensure that the underlying native connection is not released if a datastore transaction is in progress.

import java.sql.Connection;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;

...

EntityManager em = emf.createEntityManager();
Connection conn = (Connection) em.unwrap(java.sql.Connection.class);

// do JDBC stuff

conn.close();

The example below shows how to use a connection directly from the DataSource, rather than using an EntityManager 's connection.

import java.sql.*;
import javax.sql.*;
import org.apache.openjpa.conf.*;
import org.apache.openjpa.persistence.*;

...

OpenJPAEntityManagerFactory kemf = OpenJPAPersistence.cast(emf);
OpenJPAConfiguration conf = kemf.getConfiguration();
DataSource dataSource = (DataSource) conf.getConnectionFactory();
Connection conn = dataSource.getConnection();

// do JDBC stuff

conn.close();